1. Field of the Invention
This invention relates generally to tape cassettes, and more particularly is directed to improvements in magnetic tape cassettes provided with reel brake assemblies which are engaged or operative when the cassette is not in use.
2. Description of the Prior Art
Recently, it has been proposed to provide an improved cassette recording and/or reproducing apparatus in which a magnetic tape extending between supply and take-up reels contained in a cassette housing may be withdrawn from the housing for the high quality recording and reproducing of information signals on the tape. Generally, the tape cassette provided for use in such an apparatus has a relatively large opening in the peripheral wall of the cassette housing to permit the magnetic tape to be withdrawn therethrough. Therefore, if the magnetic tape is loosened, as by turning of one or both of the reels in the direction for unwinding the tape therefrom while the cassette is not in use, there is the danger that the loosened tape may inadvertently exit from the housing through the large opening of the latter and thus be succeptible to being damaged or even severed. Even if the loosened tape does not exit from the cassette housing, it is possible that the loosened tape within the housing will not be positioned so as to make possible its controlled withdrawal from the cassette housing ehen the cassette is subsequently installed on an apparatus for the recording or reproducing of information on the respective tape.
Various tape cassettes have been proposed in which braking means are provided within the cassette housing to resist unwinding or loosening of the tape when the cassette is not in use. In a particularly advantageous tape cassette provided with braking means, as aforesaid, for example, as disclosed in detail in U.S. Pat. No. 4,022,401, issued May 10, 1977, and having a common assignee herewith, each reel rotatably disposed in the cassette housing is provided with a circular series of raked teeth which define respective substantially radially directed surfaces facing in the direction of rotation of such reel for unwinding of the tape therefrom, and the braking means for each reel includes a support member, preferably in the form of a pivoted lever, movable in the cassette housing between an engaged position and a disengaged position, a pawl-like member carried by the support member to be positioned against the raked teeth of the respective reel in the engaged position of the support and being spaced from the raked teeth in the disengaged position, and means mounting the pawl-like member for angular displacement in respect to the support member. When the support member is in its engaged position, rotation of the respective reel in the direction for rewinding the tape thereon causes the raked teeth to skip or move past the pawl-like member as the latter is angularly displaced in one direction relative to its support member so as to substantially free the reel for rotation in the tape rewinding direction, whereas rotation of the reel in the tape unwinding direction brings one of the substantially radially directed surfaces of the raked teeth against the pawl-like member so as to urge the latter to be angularly displaced in the opposite direction relative to its support member. Further, abutment means are preferably fixed in respect to the cassette housing and are engageable by the pawl-like member in the engaged position of its support member for blocking the angular displacement of the pawl-like member in said opposite direction relative to its support member, thereby to prevent unwinding of the tape from the associated reel. Further, in the existing tape cassette being described, a torsion spring of resilient wire of the like is formed separate from the remainder of the braking means and is assembled in respect to each pivoted support member so as to yieldably urge the latter to its engaged position, and the cassette housing has an opening at which a portion of the support member is accessible from the exterior of the housing for actuation of the pivoted support member or lever to its disengaged position against the force of the respective spring. Although it has been proposed, in connection with the tape cassette being described, to form each support member, the respective pawl-like member and the means by which the latter is mounted on the support member as integral parts of a one-piece molded-plastic element, it has been found that the production and assembly of the described braking means having an independent torsion or coil spring for urging each pivoted support member to its engaged position are relatively time consuming and costly.